Final answer:
Unilineal descent is the system that establishes descent group membership exclusively through the male or female line, with patrilineal and matrilineal descent being its two main forms.
Step-by-step explanation:
The type of descent group membership that establishes lineage exclusively through the male or the female line is called unilineal descent. There are two main forms of unilineal descent: patrilineal descent, which traces an individual's kinship through the male ancestors, and matrilineal descent, which traces it through female ancestors. On the other hand, ambilineal descent allows for a choice between the male or female line, and bilaterial descent (also known as bilineal descent) traces kinship through both parents' lines.